(1) Field of the Invention
The present invention relates to a communication monitoring and controlling apparatus, and more particularly to a communication monitoring and controlling apparatus in an existing network of communication equipment which is connected to a new-type network which comprises a plurality of network elements and an operation system.
(2) Description of the Related Art
New-type networks may be SDH (Synchronous Digital Hierarchy) communication networks, for example, and existing networks may be PDH (Presiochronous Digital Hierarchy) communication networks, for example.
The existing PDH communication networks have been associated with a monitoring and controlling system using local interfaces and protocols. For SDH communication networks newly recommended by ITU-T (International Telecommunication Union-Telecommunication Sector), there has been recommended a standardized monitoring and controlling system. In view of the standardized monitoring and controlling system recommended for SDH communication networks, there have been growing demands for combining a conventional local PDH communication network monitoring and controlling system with the standardized monitoring and controlling system, for monitoring the existing PDH communication networks. Various efforts have been made in the art to meet such demands.
In communities where communication networks are to be newly introduced, such as those in developing countries, a transmission rate of 150 Mbps used by SDH communication networks is too high for communities including towns and villages where the population is relatively small, regardless of the fact that SDH communication networks will be a mainstream standard system in the future. Accordingly, those regions have seen the need for PDH communication network systems which use low and medium transmission rates of 2 Mbps.times.4 communication links, 2 Mbps.times.16 communication links, and 34 Mbps.times.1 communication link and entail a relatively low facility cost.
However, although PDH communication network systems play a major role in signal transmission for a while in such small-scale communities in developing countries, such developing countries naturally have plans to introduce an SDH communication network between large cities to interconnect the PDH communication networks in the near future.
In view of such plans, it is necessary to introduce PDH communication networks with their monitoring and controlling system designed in conformity with a standardized SDH monitoring system, so that an SDH communication network which will be introduced in the near future can be monitored in an integrated fashion by a standardized monitoring and controlling system without any special modifications or additions.
The present invention is not concerned with a process for integrating an existing PDH communication network monitoring and control system with an SDH communication network monitoring and control system, but with the provision of a PDH communication network monitoring and control system, which can newly be installed, taking into account a possible combination in the future with an SDH communication network monitoring and control system for an integrated network monitoring capability.
A first conventional arrangement will be described below.
FIG. 21 of the accompanying drawings shows a conventional PDH/SDH converting apparatus which is designed to integrate an existing PDH monitoring and controlling system with an SDH communication network monitoring and control system.
As shown in FIG. 21, an SDH communication network comprises a plurality of network elements (hereinafter referred to as "NE") 101-105 and an operation system 106, and a PDH communication network comprises PDH units 107-109. The PDH communication network has standard communication converters 110-112 associated respectively with the PDH units 107-109 and positioned in a region where the PDH communication network is held in contact with the SDH communication network. The standard communication converters 110-112 are capable of converting monitoring and controlling information according to local interface specifications of the PDH communication network into monitoring and controlling information according to standard interface specifications of the SDH communication network, and vice versa. With these capabilities of the standard communication converters 110-112, the PDH units 107-109 may be seen as respective NEs when viewed from the operation system 106, and can be handled as equivalents to NEs of the SDH communication network.
The standard communication converters 110-112 are combined with the PDH unit 107, and they jointly serve as a PDH/SDH converting apparatus 113.
A second conventional arrangement will be described below.
FIG. 22 of the accompanying drawings shows the conventional communication system shown in FIG. 21, as viewed from a different viewpoint. In FIG. 22, the operation system 106 shown in FIG. 21 is referred to as a host system 114, the PDH/SDH converting apparatus 113 as a master office 115, and the PDH unit 108 as a slave office 116. NEs 117, 118 are connected to the master office 115, and the host system 114 is directly connected to the master office 115 though the host system 114 may be connected to any one of the NEs of the SDH communication network without any change in its functions. While only one slave office 116 is shown in FIG. 22, there are actually a plurality of slave offices in the PDH communication network.
When the host system 114 is to read setting information of the slave office 116, the host system 114 transmits a reading request, which is received by a host interface 115a of the master office 115. The host interface 115a has the functions of the standard communication converters 110-112 shown in FIG. 21. The received reading request is converted into local interface specifications by the host interface 115a, and then transferred from an interoffice communication unit 115b to an interoffice communication unit 116a of the slave office 116, from which the reading request is sent to a setting change processor 116b. In response to the reading request from the setting change processor 116b, setting information is read from a setting storage unit 116c and sent to the interoffice communication unit 116a. The setting information is then transmitted from the interoffice communication unit 116a through the interoffice communication unit 115b and the host interface 115a to the host system 114.
A third conventional arrangement will be described below.
In FIG. 22, the operator accesses (logs in) each of the NEs via the host system 114. The monitoring and controlling system of the SDH communication network incorporates a security function for preventing an unauthorized person from operating the host system 114 in an attempt to change settings and control the NEs for protection against communication system failures.
Specifically, identification names (user names), passwords, and security levels of the operators who are allowed to access the NEs are registered in the NEs. When an access request is sent from the host system 114 to an NE, the access request is accompanied by the user name and password of the operator. If the user name and the password are registered in the NE, then the NE permits the operator to operate the NE at the corresponding security level registered in the NE.
Local terminals for changing settings are connected to the respective slave offices. A local terminal for changing settings is also connected to the master office 115 because the master office 115 has functions as a slave office. These local terminals register identification names (user names) and security levels of the operators who are allowed to operate the local terminals. Therefore, only authorized persons or operators are allowed to operate the local terminals.
According to the first conventional arrangement, in order for the operation system 106 to obtain monitoring information from the PDH units 107-109, it is necessary for the operation system 106 to log in or be associated with the PDH units 107-109. However, since the PDH communication network, which is of a low or medium transmission rate, has a relatively small amount of monitoring information, such a logging-in or associating process is rather tedious and time-consuming.
Each of the standard communication converters 110-112 requires a large-capacity storage unit and a complex logic circuit, and as many standard communication converters 110-112 as the number of PDH units 107-109 are needed. Therefore, the overall PDH communication network is excessively large in hardware and software scale.
According to the second conventional arrangement, the host system 114 is usually operated by a human operator, and the networks are required to send a quick response in reply to a request made by such a human operator. When the host system 114 is to read setting information of the slave office 116, a reading request is sent from the host system 114 through the master office 115 to the slave office 116, and a response is sent from the slave office 116 through the master office 115 to the host system 114. Therefore, if there are many slave offices, then a relatively long period of time is needed until the host system 114 receives responses from all the slave offices after having transmitted a reading request.
Generally, it is necessary for the host system 114 and the slave offices to have the same monitoring information, the same controlling information, and the same setting information. No problem arises insofar as settings are established in the slave offices and the slave offices are controlled by the host system 114. However, when settings are changed directly by slave offices, the setting information in the host system 114 becomes different from the setting information in the slave offices. Therefore, the host system 114 has heretofore been required to send a reading request periodically to the slave offices in order to recognize any unknown changes in the settings, and update its own stored setting information based on responses received from the slave offices. Such a periodic setting information updating process is tedious and timeconsuming.
Furthermore, since different processes are needed to establish settings from the host system 114 and change settings locally from the slave offices, the processes carried out by the host system 114 and the slave offices are complicated.
For initializing setting information, it is necessary to transmit and receive initializing information between the host system 114, the master office 115, and the slave offices 116. The amount of communications required to transmit and receive such initializing information tends to reduce the efficiency of transfer of monitoring and controlling information.
According to the third conventional arrangement, the security function of the monitoring and controlling system of the SDH communication network has been sufficient if it does not cover the PDH communication network. However, if the monitoring and controlling system should cover the PDH communication network as well as the SDH communication network, then it is necessary to establish settings in, control, and monitor the PDH units (slave offices), and hence each of the slave offices needs a security function.
Once the networks are constructed, it is possible to access the individual slave offices from the host system 114 via the master office 115. However, when the slave offices are set up after they are delivered until the networks are constructed, each of the slave offices needs a function to allow itself to be directly logged in. Many instances in maintenance activities require individual slave offices to be locally logged in. Accordingly, not only the master offices, but also the individual slave offices, need a security function.
When an operator who is registered in a local terminal accesses a slave office connected to the local terminal via the local terminal, the operator can gain access to all the slave offices via the local terminal. It has been unable to establish security separately with respect to each of the slave offices.